The Seattle Longitudinal Study (SLS) which has investigated cognitive development in adults over a 28 year period is to be extended over another seven-year interval including the acquisition of a sixth wave panel. The core project supports the maintenance of panels and data archives. The four subprojects extend the study into new directions; (1) A family resemblance study will recruit 900 children and 600 siblings of current and former SLS participants, to investigate generational shifts in ability status across generations, and to examine parent-offspring and sibling correlations in cognitive abilities, not heitherto examined in adults. (2) A health history study involves secondary data analyses of the relationship between (a) disease, intellectual stability and decline, and (b) of the relationship between the occurrence of disease and effectiveness of cognitive training in the remediation of intellectual decline. Health histories will be updated for all subjects assessed in the 1983-85 cycle, as well as for the longitudinal subjects to be assessed in the proposed 1990-92 cycle. (3) A seven-year follow-up study on the long-term effects of cognitive training and practice will investigate how such interventions affect both level and rate of cognitive aging. Approximately 300 participants will receive 5 hours of cognitive training on Inductive Reasoning or Spatial Orientation as well as a 5 hour pretest/ posttest battery. Practice effects will be assessed with approximately 200 matched control participants. Cohort effects in cognitive training, the effectiveness of brief booster training procedures and transfer of training to real life tasks will also be examined. (4) A sixth wave of the longitudinal study of cognitive functioning will permit further investigation of the impact of demographic changes upon adult cognitive development in the pre-babyboom and babyboom cohorts. In this study approximately 1000 longitudinal subjects will be retested, and a new panel of 650 subjects will be initially assessed on a 5 hour psychometric test battery. This study will generate data suitable for the seven-year assessment of longitudinal changes in ability factor structure from young adulthood through advanced old age.